Steering Horn Switch Inversion and Sealing
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Solution Overview
Problem
Existing horn systems in vehicles face issues with unreliable actuation due to high force requirements and potential inadvertent activation from vibrations, and they often have an aesthetically undesirable gap between the air bag cover and the steering wheel hub, allowing dust and contaminants to enter.
Innovation Solution
A steering assembly with a base plate connected to a hub, featuring a horn grounding switch with a ground contact that moves between a normally closed and open position in response to selectable forces, utilizing a dampener and spring mechanism to bias the ground contact and minimize the gap between components, thereby reducing the force needed to actuate the horn and preventing unintended activation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the air bag module is pushed with sufficient force to overcome the biasing force of the springs to close the horn circuit, then the horn can be actuated, but the force required may be higher than necessary and may cause inadvertent actuation under vibration
Solution Approach 1:
The patent inverts the traditional horn switch mechanism by using a normally closed contact that opens upon actuation, rather than a normally open contact that closes. The spring biases the contact to remain closed, and actuation forces the contact open against the spring force. This inversion reduces the required actuation force while preventing inadvertent activation through the inherent mechanical advantage of the biased contact system.
Solution Approach 2:
The patent changes the spring force parameter to optimize the balance between contact pressure and actuation force. By carefully selecting the spring constant and pre-compression, the system achieves reliable contact closure with minimal force while maintaining sufficient contact pressure for reliable electrical connection. The spring parameters are tuned to differentiate between intentional actuation and vibration-induced movements.
2Ease of manufacture
If the air bag module is secured onto the steering wheel hub, then the horn system is assembled, but an aesthetically undesirable gap is present between the air bag cover and the steering wheel hub allowing dust and contaminants to enter
Solution Approach 1:
The patent introduces a sealing element or gasket as an intermediary component between the air bag cover and the steering wheel hub. This sealing intermediary fills the gap that would otherwise allow dust and contaminants to enter, while maintaining the simple assembly process. The sealing element can be compressed during assembly to create an effective barrier without requiring complex assembly procedures.
3Reliability
If the ground contact is biased away from the electrical ground, then the horn circuit remains open for normal operation, but excessive force is required to close the circuit for horn actuation
Solution Approach 1:
The patent inverts the traditional switch mechanism by using a normally closed contact that opens upon actuation. The spring biases the ground contact to remain closed against the electrical ground, providing reliable circuit control during normal operation. When actuation force is applied, the contact opens against the spring bias, creating the horn signal. This inversion reduces the force required compared to overcoming a strong biasing force to close a normally open contact.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution provides reliable and efficient control of the vehicle horn with reduced force requirements and minimizes the gap between the air bag cover and the steering wheel hub, enhancing both functionality and aesthetics by preventing dust ingress.
Implementation Method 1
A biasing force directs the ground contact to a normally closed position in electrical communication with the vehicle electrical ground
Implementation Method 2
A dampener is coupled to the base plate and the ground contact
Data Source
AI summary
Various implementations include a steering assembly including a hub assembly and airbag module. The hub assembly includes one or more hub assembly attachment tabs each defining a fastener opening. The airbag module includes one or more airbag module attachment tabs each defining a fastener opening. One of the hub assembly or the airbag module includes one or more temporary fasteners, and each of the temporary fasteners is couplable to a portion of the other of the hub assembly or the airbag module. One of the hub assembly or the airbag module includes one or more alignment portions structured to align each fastener opening in the hub assembly attachment tabs with a respective fastener opening in one of the airbag module attachment tabs when the temporary fasteners of the hub assembly or the airbag module are coupled to the portion of the other of the hub assembly or the airbag module.